1. Field of the Invention
The present invention relates to a wireless communication system. And, more particularly, the present invention relates to a method for transmitting ACK/NACK signal in a wireless communication system applied carrier aggregation and apparatus therefor.
2. Discussion of the Related Art
As an example of a wireless communication system to which the present invention may be applied, a 3GPP LTE (3rd Generation Partnership Project Long Term Evolution; hereinafter referred to as “LTE”) communication system will now be broadly described.
FIG. 1 illustrates a general view of an E-UMTS network structure as an example of a wireless communication system. Herein, the E-UMTS (Evolved Universal Mobile Telecommunications System) corresponds to a system evolved from the conventional UMTS (Universal Mobile Telecommunications System). The 3GPP is presently carrying out a basic standardization process for the E-UMTS. Generally, the E-UMTS may also be referred to as an LTE system. For details of the technical specifications of the UMTS and the E-UMTS, reference may be made to Release 7 and Release 8 of “3rd Generation Partnership Project; Technical Specification Group Radio Access Network”.
Referring to FIG. 1, the E-UMTS includes a User Equipment (UE) (120), base stations (eNode B; eNB) 110a and 110b, and an Access Gateway (AG) which is located at an end of a network (E-UTRAN) and connected to an external network. The base stations can simultaneously transmit multiple data streams for a broadcast service, a multicast service and/or a unicast service.
One or more cells may exist for one base station. One cell is set to one of bandwidths of 1.25, 2.5, 5, 10, and 20 Mhz to provide a downlink or uplink transport service to several user equipments. Different cells may be set to provide different bandwidths. Also, one base station controls data transmission and reception for a plurality of user equipments. The base station transmits Downlink (DL) scheduling information of downlink data to the corresponding user equipment to notify information related to time and frequency domains to which data will be transmitted, encoding, data size, and HARQ (Hybrid Automatic Repeat and reQuest). Also, the base station transmits Uplink (UL) scheduling information of uplink data to the corresponding user equipment to notify information related to time and frequency domains that can be used by the corresponding user equipment, encoding, data size, and HARQ. An interface for transmitting user traffic or control traffic can be used between the base stations. A Core Network (CN) may include the AG and a network node or the like for user registration of the UE. The AG manages mobility of a UE on a TA (Tracking Area) basis, wherein one TA includes a plurality of cells.
The wireless communication technology has been developed up to the LTE based upon WCDMA. However, the demands and expectations of the users and the manufacturers and providers are growing continuously. Also, since other wireless access technologies are constantly being developed, the wireless communication technology is required to newly evolve in order to ensure competiveness in the future. Accordingly, characteristics, such as reduced cost for each bit, increased service availability, usage of a flexible frequency band, simple structure and open interface, and adequate power consumption of the user equipment are being requested.
Recently, a standardization procedure for a succeeding (or subsequent) technology of the LTE has been under progress by the 3GPP. In the description of the present invention, the above-mentioned technology will be referred to as “LTE-Advanced” or “LTE-A”. The essential difference between the LTE system and the LTE-A system is the system bandwidth. The LTE-A system aims to support a broadband of up to 100 MHz. For this, the LTE-A system encourages the use of a carrier aggregation (or bandwidth aggregation) technology, which achieves a broadband by using multiple component carriers. In order to use a wider (or broader) frequency band, the carrier aggregation (or bandwidth aggregation) uses a plurality of component carriers as a single large logical frequency band. The bandwidth of each component carrier (or bandwidth carrier) may be defined based upon the bandwidth of a system block used in the LTE system. Each component carrier (or bandwidth carrier) uses a component carrier (or bandwidth carrier) so as to be transmitted.
The present invention is devised to provide a method for transmitting a control signals and an apparatus of the same in a wireless communication system. Also, the present invention is devised to provide a method for transmitting ACK/NACK signal in a wireless communication system applied carrier aggregation and apparatus therefore.
The technical objectives that are to be realized by the present invention will not be limited only to the technical objects pointed out herein. Other technical objectives that have not yet been mentioned herein will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
In an aspect of the present invention, a method for transmitting ACK/NACK (Acknowledgement/Negative-ACK) state information in a wireless communication system includes receiving multiple transmission blocks respectively through multiple downlink component carriers from a base station; determining ACK/NACK responses corresponding to each of the multiple transmission blocks by decoding the multiple transmission blocks; mapping the ACK/NACK responses to a ACK/NACK state information; and transmitting the ACK/NACK state information through a single uplink component carrier, wherein ACK information included in the ACK/NACK state information indicates a number of ACK response among the ACK/NACK responses. Herein, NACK information included in the ACK/NACK state information may indicate a case where decoding of the multiple transmission blocks all failed.
Also, in the receiving multiple transmission blocks, two or more transmission blocks may be received through at least one downlink component carrier among the multiple downlink component carriers.
Preferably, the step of mapping to the ACK/NACK state information may include a step of mapping a predetermined number of ACK/NACK responses among the ACK/NACK responses to the ACK/NACK state information. Also, the step of transmitting the ACK/NACK state information to the base station may include transmitting the ACK/NACK state information by using one or more PUCCH (Physical Uplink Control CHannel) resources included in the one uplink component carrier.
More preferably, the step of transmitting to the base station may further include modulating the ACK/NACK state information using QPSK (Quadrature Phase Shift Keying).
In another aspect of the present invention, a user equipment includes a receiving module for receiving multiple transmission blocks respectively through multiple downlink component carriers from a base station; a processor for determining ACK/NACK responses corresponding to each of the multiple transmission blocks by decoding the multiple transmission blocks, and for mapping the ACK/NACK responses to a ACK/NACK state information; and a transmitting module for transmitting the ACK/NACK state information through a single uplink component carrier, wherein ACK information included in the ACK/NACK state information indicates a number of ACK response among the ACK/NACK responses. Herein, NACK information included in the ACK/NACK state information may indicate a case where decoding of the multiple transmission blocks all failed.
The receiving module may receive two or more transmission blocks through at least one downlink component carrier among the multiple downlink component carriers. And, the processor may map a predetermined number of ACK/NACK responses among the ACK/NACK responses to the ACK/NACK state information.
Also, the transmitting module may transmit the ACK/NACK state information by using one or more PUCCH (Physical Uplink Control CHannel) resources included in the one uplink component carrier. And, the processor may modulate the ACK/NACK state information using QPSK (Quadrature Phase Shift Keying).
According to the embodiments of the present invention, in a wireless communication system applying carrier aggregation, the ACK/NACK signal may be efficiently transmitted.
The effects that can be achieved in the present invention will not be limited only to the effects pointed out in the description of the present invention. Other effects that have not yet been mentioned herein will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.